A heads-up display (HUD) can be implemented to provide a virtual image (e.g., images, text, or the like) superimposed onto a real world view. Common applications of HUDs include defense, transportation, industrial, entertainment, wearable devices, or the like.
In some HUD displays, the virtual image may be presented to a user by reflecting the virtual image off of a projection surface into a user's eye. The projection surface may be transparent to allow the user to view a real world scene simultaneously with the virtual image. Accordingly, ambient light from outside of the HUD is also incident on the user's eye. The brightness and/or the uniformity of the brightness of the ambient light may affect the ability of the user to see the virtual image.